function for creating augmented matrix

anurupmitra commented 6 years ago

Hi,

I could not see any obvious (read straight-forward) method to create an augmented matrix - either by adding a block of rows OR a block of columns.

This would be invaluable.

Thanks and Regards Anurup

davidedc commented 6 years ago

Hi Anurup,

ok, say, C = A|B

short version:

retaining the "block" information (i.e. symbolically keeping track that C is a block matrix) is probably hard
just copying a matrix content to the side of another matrix would be much easier, but all further symbolic handling of the block parts would be lost

longer version:

...the symbolic part is tricky, so if one says C = A|B, then we need to define how "|" behaves for all the operations... that could end up to be quite complicated, see for example https://scicomp.stackexchange.com/questions/14164/symbolic-computations-with-block-matrices-in-maple for how Maple and SymPy do it.

The alternative is to "just" create a function that copies a matrix to the side of another one, so all "symbolic" information about "C" being constituted by "A" and "B" is lost.

That could be made to work more quickly, but I need to think about good names and possible gotchas...

If you have further thoughts let me know...

anurupmitra commented 6 years ago

Hi Davide,

Thank you for your reply and sorry for the delay in getting back to you.

I'll be selfish - for my personal usage case - the last option would be most useful. In fact, I need a glorified addRow(s) and addCol(s) function. The symbolic information is not important. The new matrices that will be formed are.

Thanks again for your great work!

Regards Anurup

davidedc / Algebrite

function for creating augmented matrix #59